Optical properties of molecular beam epitaxy-grown $Zn1−xMnxTe$ thin films measured by complementary techniques

By using a combination of prism coupler, reflectivity, and spectroscopic ellipsometry techniques, we have determined the dielectric function of a series of molecular beam epitaxy-grown $Zn1−xMnxTe$ thin films. These results have enabled us to determine the critical point parameters that correspond to the electronic transitions in the Brillouin zone for this particular alloy family. We find that, although the fundamental band gap $E0$ increases with x for this alloy, $E1$ and $E1+Δ1$ transition energies decrease with x for the $Zn1−xMnxTe$ system, in contrast to most other zinc-blende semiconductor alloys.